Valve characteristics control apparatus

ABSTRACT

A control valve part switches a flowing direction of working fluid between a first advance chamber and a first retard chamber in a timing adjustment mode, and restricts working fluid from flowing between the first advance chamber and the first retard chamber in a working angle adjustment mode. A check valve part allows working fluid to flow from a second retard chamber through a check passage to a second advance chamber, and restricts working fluid from flowing from the second advance chamber through the check passage to the second retard chamber. A switch valve part allows a communication between the second advance chamber and the second retard chamber through a switch passage in the working angle adjustment mode, and prohibits the communication between the second advance chamber and the second retard chamber through the switch passage in the timing adjustment mode.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on Japanese Patent Application No. 2011-147821filed on Jul. 3, 2011, the disclosure of which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a valve characteristics controlapparatus.

BACKGROUND

JP-A-2004-183612 (U.S. Pat. No. 7,047,922) describes a valvecharacteristics control apparatus that controls a valve timing and avalve working angle as valve characteristics of a valve of an internalcombustion engine.

In the valve characteristics control apparatus, a motor is engaged witha camshaft through a gear train. The motor controls the valve timing andthe valve working angle by varying the rotating speed of the camshaftfrom a basic velocity that is set as a half of a rotating speed of acrankshaft.

The valve characteristics control apparatus is required to electricallyaccurately control the rotating speed of the motor, which determines therotating speed of the camshaft, while the rotating speed of thecrankshaft of the combustion engine is varied every moment. However, anacting direction of a variation torque applied to the camshaft from aspring reaction force of the valve is alternately changed in accordancewith the rotation of the crankshaft. Therefore, it is difficult toaccurately control the rotating speed of the motor, while the variationtorque is absorbed by a torque generated by the motor, so that theaccuracy of controlling the valve characteristics may become low.

SUMMARY

According to a first example of the present disclosure, a valvecharacteristics control apparatus that controls valve characteristics ofa valve opened and closed by a rotation of a camshaft in accordance witha rotation of a crankshaft in an internal combustion engine includes ahousing rotating with the crankshaft; a first vane rotor; a controlvalve part; a second vane rotor; a check valve part; and a switch valvepart. The first vane rotor has a first vane rotatably received in thehousing, and a first advance chamber and a first retard chamber aredefined by partitioning a space between the housing and the first vanein a rotation direction. The first vane rotor has a relative rotationwith respect to the housing in an advance direction when working fluidis introduced into the first advance chamber and when working fluid isdischarged from the first retard chamber. The first vane rotor has arelative rotation with respect to the housing in a retard direction whenworking fluid is discharged from the first advance chamber and whenworking fluid is introduced into the first retard chamber. The controlvalve part switches a flowing direction of working fluid between thefirst advance chamber and the first retard chamber in a timingadjustment mode adjusting valve timing as the valve characteristics, andrestricts working fluid from flowing between the first advance chamberand the first retard chamber in a working angle adjustment modeadjusting a valve working angle as the valve characteristics. The secondvane rotor has a second vane rotating with the camshaft in a state thatthe second vane is projected into the first vane in the housing, and asecond advance chamber and a second retard chamber are defined bypartitioning a space between the first vane and the second vane in therotation direction. The second vane rotor has a relative rotation withrespect to the first vane rotor in the advance direction when workingfluid is introduced into the second advance chamber and when workingfluid is discharged from the second retard chamber. The second vanerotor has a relative rotation with respect to the first vane rotor inthe retard direction when working fluid is discharged from the secondadvance chamber and when working fluid is introduced into the secondretard chamber. The check valve part has a check passage connecting thesecond advance chamber and the second retard chamber with each other.The check valve part allows working fluid to flow from the second retardchamber through the check passage to the second advance chamber, andrestricts working fluid from flowing from the second advance chamberthrough the check passage to the second retard chamber. The switch valvepart has a switch passage connecting the second advance chamber and thesecond retard chamber with each other. The switch valve part allows acommunication between the second advance chamber and the second retardchamber through the switch passage in the working angle adjustment mode,and prohibits the communication between the second advance chamber andthe second retard chamber through the switch passage in the timingadjustment mode.

According to a second example of the present disclosure, a valvecharacteristics control apparatus that controls valve characteristics ofa valve opened and closed by a rotation of a camshaft in accordance witha rotation of a crankshaft in an internal combustion engine includes ahousing rotating with the crankshaft; a first vane rotor; a controlvalve part; a second vane rotor; a check valve part; and a switch valvepart. The first vane rotor has a first vane rotatably received in thehousing, and a first advance chamber and a first retard chamber aredefined by partitioning a space between the housing and the first vanein a rotation direction. The first vane rotor has a relative rotationwith respect to the housing in an advance direction when working fluidis introduced into the first advance chamber and when working fluid isdischarged from the first retard chamber. The first vane rotor has arelative rotation with respect to the housing in a retard direction whenworking fluid is discharged from the first advance chamber and whenworking fluid is introduced into the first retard chamber. The controlvalve part switches a flowing direction of working fluid between thefirst advance chamber and the first retard chamber in a timingadjustment mode adjusting valve timing as the valve characteristics, andrestricts working fluid from flowing between the first advance chamberand the first retard chamber in a working angle adjustment modeadjusting a valve working angle as the valve characteristics. The secondvane rotor has a second vane rotating with the camshaft in a state thatthe second vane is projected into the first vane in the housing, and asecond advance chamber and a second retard chamber are defined bypartitioning a space between the first vane and the second vane in therotation direction. The second vane rotor has a relative rotation withrespect to the first vane rotor in the advance direction when workingfluid is introduced into the second advance chamber and when workingfluid is discharged from the second retard chamber. The second vanerotor has a relative rotation with respect to the first vane rotor inthe retard direction when working fluid is discharged from the secondadvance chamber and when working fluid is introduced into the secondretard chamber. The check valve part has a check passage connecting thesecond advance chamber and the second retard chamber with each other.The check valve part allows working fluid to flow from the secondadvance chamber through the check passage to the second retard chamber,and restricts working fluid from flowing from the second retard chamberthrough the check passage to the second advance chamber. The switchvalve part has a switch passage connecting the second advance chamberand the second retard chamber with each other. The switch valve partallows a communication between the second advance chamber and the secondretard chamber through the switch passage in the working angleadjustment mode, and prohibits the communication between the secondadvance chamber and the second retard chamber through the switch passagein the timing adjustment mode.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentdisclosure will become more apparent from the following detaileddescription made with reference to the accompanying drawings. In thedrawings:

FIG. 1 is a schematic view illustrating a valve characteristics controlapparatus according to a first embodiment;

FIG. 2 is a cross-sectional view taken along a line II-II of FIG. 1;

FIG. 3 is a schematic view illustrating the valve characteristicscontrol apparatus of the first embodiment in an operation statedifferent from FIG. 1;

FIG. 4 is a schematic cross-sectional view illustrating the valvecharacteristics control apparatus of the first embodiment where a spoolis located at an advance position in a timing adjustment mode;

FIG. 5 is a schematic cross-sectional view illustrating the valvecharacteristics control apparatus of the first embodiment where thespool is located at a retard position in the timing adjustment mode;

FIG. 6 is a schematic cross-sectional view illustrating the valvecharacteristics control apparatus of the first embodiment where thespool is located at a hold position in the timing adjustment mode;

FIG. 7 is a schematic cross-sectional view illustrating the valvecharacteristics control apparatus of the first embodiment in anoperation state of a working angle adjustment mode;

FIG. 8 is a schematic cross-sectional view illustrating the valvecharacteristics control apparatus of the first embodiment in anoperation state of the working angle adjustment mode different from FIG.7;

FIG. 9 is a graph illustrating a relationship between a crank angle anda variation in torque applied to the valve characteristics controlapparatus;

FIG. 10 is a characteristics view illustrating characteristics of thevalve characteristics control apparatus of the first embodiment;

FIG. 11 is a view illustrating advantage of the valve characteristicscontrol apparatus;

FIG. 12 is a schematic cross-sectional view illustrating a valvecharacteristics control apparatus according to a second embodiment wherea spool is located at an advance position in a working angle adjustmentmode;

FIG. 13 is a schematic cross-sectional view illustrating the valvecharacteristics control apparatus of the second embodiment in anoperation state of the working angle adjustment mode;

FIG. 14 is a schematic cross-sectional view illustrating the valvecharacteristics control apparatus of the second embodiment in anoperation state of the working angle adjustment mode different from FIG.13;

FIG. 15 is a characteristics view illustrating characteristics of thevalve characteristics control apparatus of the second embodiment;

FIG. 16 is a characteristics view illustrating characteristics of thevalve characteristics control apparatus of the second embodiment;

FIG. 17 is a view illustrating advantage of the valve characteristicscontrol apparatus;

FIG. 18 is a schematic cross-sectional view illustrating a valvecharacteristics control apparatus according to a third embodiment wherea spool is located at an advance position in a timing adjustment mode;

FIG. 19 is a schematic cross-sectional view illustrating the valvecharacteristics control apparatus of the third embodiment where thespool is located at a retard position in the timing adjustment mode;

FIG. 20 is a schematic cross-sectional view illustrating the valvecharacteristics control apparatus of the third embodiment where thespool is located at a hold position in the timing adjustment mode;

FIG. 21 is a schematic cross-sectional view illustrating the valvecharacteristics control apparatus of the third embodiment in anoperation state of a working angle adjustment mode;

FIG. 22 is a schematic cross-sectional view illustrating the valvecharacteristics control apparatus of the third embodiment in anoperation state of the working angle adjustment mode different from FIG.21;

FIG. 23 is a characteristics view illustrating characteristics of thevalve characteristics control apparatus of the third embodiment;

FIG. 24 is a schematic cross-sectional view illustrating a valvecharacteristics control apparatus according to a fourth embodiment wherea spool is located at a retard position in a working angle adjustmentmode;

FIG. 25 is a schematic cross-sectional view illustrating the valvecharacteristics control apparatus of the fourth embodiment in anoperation state of the working angle adjustment mode;

FIG. 26 is a schematic cross-sectional view illustrating the valvecharacteristics control apparatus of the fourth embodiment in anoperation state of the working angle adjustment mode different from FIG.25;

FIG. 27 is a characteristics view illustrating characteristics of thevalve characteristics control apparatus of the fourth embodiment; and

FIG. 28 is a characteristics view illustrating characteristics of thevalve characteristics control apparatus of the fourth embodiment.

DETAILED DESCRIPTION

Embodiments of the present invention will be described hereafterreferring to drawings. In the embodiments, a part that corresponds to amatter described in a preceding embodiment may be assigned with the samereference numeral, and redundant explanation for the part may beomitted. When only a part of a configuration is described in anembodiment, another preceding embodiment may be applied to the otherparts of the configuration. The parts may be combined even if it is notexplicitly described that the parts can be combined. The embodiments maybe partially combined even if it is not explicitly described that theembodiments can be combined, provided there is no harm in thecombination.

First Embodiment

FIG. 1 illustrates a valve characteristics control apparatus 1 accordingto a first embodiment which is applied to an internal combustion engineof a vehicle. The apparatus 1 adjusts valve timing and valve workingangle for plural exhaust valves having different opening/closingtimings, as valve characteristic of a valve which is opened and closedby rotation of a camshaft 2 according to rotation of a crankshaft (notshown) in the engine. The apparatus 1 is constructed by combining arotation drive system 3 and a rotation control system 4. The drivesystem 3 is arranged in a transmission path through which the enginetorque is transmitted from the crankshaft to the camshaft 2, and thecontrol system 4 controls the drive system 3.

(Rotation Drive System)

The drive system 3 will be described with reference to FIGS. 1 and 2.The rotation drive system 3 coaxially has a housing 10, a first vanerotor 20, and a second vane rotor 30 which are integrally rotatable. Thehousing 10 and the vane rotors 20 and 30 have common rotation(circumference) direction, common axis direction, and common radialdirection. Hereinafter, description is made using the rotation(circumference) direction, the axis direction, and the radial direction.

The metal housing 10 is constructed by joining a pair of accommodationplates 13, 14 to axial ends of a main part 12, respectively, and has ahollow shape as a whole. The main part 12 has an accommodation wall 120and plural shoes 122.

As shown in FIG. 1, the cylindrical accommodation wall 120 has pluralsprocket teeth (not shown) projected outward in the radial direction andlocated with regular intervals in the rotation direction. A timing chain(not shown) is arranged between the sprocket teeth and teeth of thecrankshaft, so that the accommodation wall 120 is linked with thecrankshaft. When the engine is rotated, the engine torque output fromthe crankshaft is transmitted to the housing 10 through the timingchain, and the housing 10 is rotated in response to the rotation of thecrankshaft in a counterclockwise direction of FIG. 1.

Each of the convex shoes 122 is projected inward in the radial directionfrom the wall 120, and the shoes 122 are located with regular intervalsin the rotation direction. A first accommodation chamber 16 is definedbetween the shoes 122 located adjacent with each other in the rotationdirection.

The first vane rotor 20 is accommodated between the accommodation plates13 and 14 in the axis direction in the housing 10, and is slidablyfitted with each of the plates 13 and 14. The first vane rotor 20 hasplural rotation walls 200 and plural first vanes 202.

The rotation wall 200 partially has a cylindrical shape, and is locatedon the inner side of the corresponding shoe 122 in the radial direction.The rotation wall 200 is slidably fitted to a projection-side endportion of the corresponding shoe 122. The fitting structure allows thefirst vane rotor 20 to rotate in the counterclockwise direction and tohave relative rotation with respect to the housing 10.

The concave first vane 202 defines a second chamber 26 opening to theinner side in the radial direction by recessing outward in the radialdirection from a position between the rotation walls 200 in the rotationdirection. The first vane 202 is accommodated in the corresponding firstaccommodation chamber 16 so as to partition the chamber 16 in therotation direction, so that the first vane 202 defines a first advancechamber 16 a and a first retard chamber 16 r. That is, the first advancechamber 16 a and the first retard chamber 16 r are formed through thefirst vane 202 in the rotation direction, and are located between theshoes 122 of the housing 10 defining the first chamber 16.

A volume of the chamber 16 a, 16 r is varied by a flow of working liquidsuch as oil, and the first vane rotor 20 has relative rotation withrespect to the housing 10. Specifically, the volume of the retardchamber 16 r is reduced when working oil is discharged, and the volumeof the advance chamber 16 a is increased when working oil is introduced,so that the first vane rotor 20 has relative rotation with respect tothe housing 10 in the advance direction. As a result, the first vane 202is pressed against the shoe 122 in the advance direction, and therelative rotation phase of the first vane rotor 20 is restricted frombeing varied in the advance direction relative to the housing 10.

In contrast, the volume of the advance chamber 16 a is reduced whenworking oil is discharged, and the volume of the retard chamber 16 r isincreased when working oil is introduced, so that the first vane rotor20 has relative rotation with respect to the housing 10 in the retarddirection. As a result, the first vane 202 is pressed against the shoe122 in the retard direction, and the relative rotation phase of thefirst vane rotor 20 is restricted from being varied in the retarddirection relative to the housing 10.

The second vane rotor 30 made of metal is accommodated between theaccommodation plates 13 and 14 in the axis direction in the housing 10,and is slidably fitted with each of the plates 13 and 14. The secondvane rotor 30 has a rotation shaft 300 and plural second vanes 302.

The cylindrical rotation shaft 300 is arranged on the inner side of therotation wall 200 of the first vane rotor 20 in the radial direction,and is coaxially linked with the camshaft 2 in a state where the shaft300 is slidably fitted with the wall 200. Therefore, the second vanerotor 30 rotates in the counterclockwise direction together with thecamshaft 2 and is able to have relative rotation with respect to thefirst vane rotor 20 and the housing 10.

Each of the convex second vanes 302 is projected outward in the radialdirection from the shaft 300, and the second vanes 302 are located withregular intervals in the rotation direction. The second vane 302 isaccommodated and projected into the corresponding second accommodationchamber 26 so as to partition the chamber 26 in the rotation direction,so that the second vane 302 defines a second advance chamber 26 a and asecond retard chamber 26 r. That is, the second advance chamber 26 a andthe second retard chamber 26 r are formed through the second vane 302 inthe rotation direction, and are located in the first vane 202 definingthe second chamber 26.

A volume of the chamber 26 a, 26 r is varied by a flow of working oil,and the second vane rotor 30 has relative rotation with respect to thefirst vane rotor 20. Specifically, the volume of the retard chamber 26 ris reduced when working oil is discharged, and the volume of the advancechamber 26 a is increased when working oil is introduced, so that thesecond vane rotor 30 has relative rotation with respect to the firstvane rotor 20 in the advance direction. As a result, the second vane 302is pressed against an inner surface 202 a of the first vane 202 in theadvance direction, and the relative rotation phase of the second vanerotor 30 is restricted from being varied in the advance directionrelative to the first vane rotor 20.

In contrast, the volume of the advance chamber 26 a is reduced whenworking oil is discharged, and the volume of the retard chamber 26 r isincreased when working oil is introduced, so that the second vane rotor30 has relative rotation with respect to the first vane rotor 20 in theretard direction. As a result, the second vane 302 is pressed against aninner surface 202 r of the first vane 202 in the retard direction, andthe relative rotation phase of the second vane rotor 30 is restrictedfrom being varied in the retard direction relative to the first vanerotor 20.

(Rotation Control System)

The rotation control system 4 will be described with reference to FIGS.1-8. As shown in FIG. 4, the control system 4 has a control valve part40, a first check valve part 50, a second check valve part 60, a switchvalve part 70, and a control circuit 80.

The control valve part 40 has an advance passage 42 a, a retard passage42 r, a main supply passage 42 ms, a drain passage 42 d and a solenoidvalve 44. A first end of the advance passage 42 a is branched andcommunicates with each of the first advance chambers 16 a. A first endof the retard passage 42 r is branched and communicates with each of thefirst retard chambers 16 r. The main supply passage 42 ms communicateswith a pump 6 which is a supply source of working oil. The pump 6 is amechanical pump driven by the internal combustion engine through thecrankshaft. While the engine is operated, the pump 6 pumps up workingoil from a drain pan 7 and supplies the working oil to the main supplypassage 42 ms. The drain passage 42 d is open to atmospheric air withthe drain pan 7 as a drain collecting section, and is arranged todischarge working oil to the drain pan 7.

The solenoid valve 44 is a spool valve that reciprocates a spool 443 ina sleeve 442 using a driving force generated by energizing a solenoid440 and a recovery force generated by elastic deformation of a coilspring 441 in a direction opposite from the driving force. The sleeve442 of the solenoid valve 44 has an advance port 442 a, a retard port442 r, a main supply port 442 ms, a sub supply port 442 ss, and a drainport 442 d.

The advance port 442 a communicates with the advance passage 42 a. Theretard port 442 r communicates with the retard passage 42 r. The mainsupply port 442 ms communicates with the main supply passage 42 ms. Thesub supply port 442 ss communicates with the second check valve part 60.The drain port 442 d communicates with the drain passage 42 d. Thesolenoid valve 44 allows or prohibits the communication among the ports442 a, 442 r, 442 ms, 442 ss and 442 d in accordance with the positionof the spool 443 that is driven by controlling the solenoid 440.

Specifically, the advance port 442 a communicates with the main supplyport 442 ms in the state where the spool 443 has moved to an advanceposition Pa of FIG. 4, so that working oil supplied from the pump 6 isintroduced into each first advance chamber 16 a through the main supplypassage 42 ms and the advance passage 42 a. Further, the retard port 442r communicates with the drain port 442 d through the inside of the spool443 in the state where the spool 443 is located at the advance positionPa, so that working oil of each first retard chamber 16 r is dischargedto the drain pan 7 through the retard passage 42 r and the drain passage42 d. Furthermore, the sub supply port 442 ss communicates with the mainsupply port 442 ms in the state where the spool 443 is located at theadvance position Pa, so that working oil supplied from the pump 6 isintroduced into the second check valve part 60 through the main supplypassage 42 ms.

In contrast, the retard port 442 r communicates with the main supplyport 442 ms in the state where the spool 443 has moved to a retardposition Pr of FIG. 5, so that the working oil supplied from the pump 6is introduced into each first retard chamber 16 r through the mainsupply passage 42 ms and the retard passage 42 r. Further, the advanceport 442 a communicates with the drain port 442 d through the inside ofthe spool 443 in the state where the spool 443 is located at the retardposition Pr, so that working oil of each first advance chamber 16 a isdischarged to the drain pan 7 through the advance passage 42 a and thedrain passage 42 d. Furthermore, the sub supply port 442 ss communicateswith the main supply port 442 ms in the state where the spool 443 islocated at the retard position Pr, so that working oil supplied from thepump 6 is introduced into the second check valve part 60 through themain supply passage 42 ms.

Further in contrast, when the spool 443 is moved to a hold position Phof FIGS. 6-8, the advance port 442 a and the retard port 442 r areprohibited from communicating with the other ports, so that working oilis prohibited from flowing into or out of each first advance chamber 16a and each first retard chamber 16 r. Furthermore, the sub supply port442 ss communicates with the main supply port 442 ms in the state wherethe spool 443 is located at the hold position Ph, so that working oilsupplied from the pump 6 is introduced into the second check valve part60 through the main supply passage 42 ms.

As shown in FIG. 4, the first check valve part 50 has plural checkpassages 52 and plural check valves 54. The check passage 52 is definedto penetrate the corresponding second vane 302 so as to connect thesecond advance chamber 26 a and the second retard chamber 26 r with eachother through the second vane 302. The check valve 54 is arranged in themiddle of the check passage 52 in the corresponding second vane 302.When the check valve 54 is opened, working oil flows from the secondretard chamber 26 r to the second advance chamber 26 a. Thereby, eachcheck valve 54 permits the forward feed of working oil which goes to thesecond advance chamber 26 a from the second retard chamber 26 r. On theother hand, the backward flow of working oil which goes to the secondretard chamber 26 r from the second advance chamber 26 a is regulated bythe check valve 54. Thus, the check passage 52 and the check valve 54construct the first check valve part 50, which is disposed in each ofthe second vanes 302.

As shown in FIG. 4, the second check valve part 60 has a sub supplypassage 62 ss and a check valve 64. The sub supply passage 62 sscommunicates with the sub supply port 442 ss of the solenoid valve 44and the first switch valve part 70. Thereby, even when the spool 443 islocated at any one of the positions Pa, Pr, and Ph, the sub supplypassage 62 ss supplies working oil from the pump 6 to the first switchvalve part 70 through the main supply passage 42 ms.

The check valve 64 is arranged in the middle of the sub supply passage62 ss. When the check valve 64 is opened, working oil flows from the subsupply port 442 ss to the first switch valve part 70 through the subsupply passage 62 ss. Thereby, each check valve 64 permits the forwardfeed of working oil which goes to the first switch valve part 70 fromthe sub supply port 442 ss. On the other hand, the backward flow ofworking oil which goes to the sub supply port 442 ss from the firstswitch valve part 70 is regulated by the check valve 64. Thereby, whenthe spool 443 is located at one of the positions Pa, Pr, and Ph, thecheck valve 64 permits the forward feed of working oil which goes to asupply point 720 of the first switch valve part 70 from the pump 6, andrestricts the backward flow having the opposite flowing direction.

The switch valve part 70 has a switch passage 72 and a solenoid valve74. A first end of the switch passage 72 is branched and communicateswith each of the second advance chambers 26 a. A second end of theswitch passage 72 is branched and communicates with each of the secondretard chambers 26 r. The switch passage 72 connects the second advancechamber 26 a and the second retard chamber 26 r with each other. Thesupply point 720 of the first switch valve part 70 is arranged in theswitch passage 72, and receives working oil from the sub supply passage62 ss by communicating with the sub supply passage 62 ss of the secondcheck valve part 60.

The solenoid valve 74 is arranged in the switch passage 72 at a positionadjacent to the second end of the switch passage 72 rather than thesupply point 720. In other words, the solenoid valve 74 is locatedadjacent to the second retard chamber 26 r rather than the supply point720. The solenoid valve 74 is driven by energizing the solenoid 740.Accordingly, the valve 74 allows the communication between the secondadvance chamber 26 a and the second retard chamber 26 r, as shown inFIGS. 7 and 8, or prohibits the communication, as shown in FIGS. 4-6.

As shown in FIG. 4, the control circuit 80 is an electronic circuitconstructed by, for example, a microcomputer. The control circuit 80 iselectrically connected to the solenoid 440, 740 of the solenoid valve44, 74 of the valve part 40, 70, and various electronic components (notshown) of the combustion engine. The control circuit 80 controls theoperational status of the combustion engine which includes energizing ofthe solenoid 440, 740 according to a computer program memorized in aninternal memory.

(Variation Torque Applied to the Vane Rotor)

Next, the variation torque which acts on the second vane rotor 30 of therotation drive system 3 of the apparatus 1 is explained with referenceto FIG. 9. During rotation of the combustion engine, the variationtorque generated by the spring reaction force from each exhaust valvethat is opened and closed by the camshaft 2 is transmitted to the secondvane rotor 30. As shown in FIG. 9, the torque is alternately variedbetween a positive torque Tr and a negative torque Ta. The positivetorque Tr acts to the first vane rotor 20 in the retard direction, andthe negative torque Ta acts to the first vane rotor 20 in the advancedirection. The positive torque Tr is generated by the spring reactionforce which resists the valve opening action of each exhaust valve. Onthe other hand, the negative torque Ta is generated by the springreaction force which assists the valve closing action of each exhaustvalve.

Characteristic operation of the apparatus 1 will be described. Thecontrol circuit 80 switches a mode of adjusting the valvecharacteristics according to the operational status of the combustionengine between a timing adjustment mode and a working angle adjustmentmode. In the timing adjustment mode, the valve timing is adjusted bymaintaining the valve working angle. In the working angle adjustmentmode, the valve working angle is adjusted by maintaining the valvetiming such as valve-closing-operation finishing timing “tec” (see FIG.10).

(Timing Adjustment Mode)

When the apparatus 1 is set to have the timing adjustment mode, thecircuit 80 controls the energizing of the solenoid 740 of the solenoidvalve 74, thereby switching the switch passage 72 to prohibit thecommunication between the second advance chamber 26 a and the secondretard chamber 26 r, as shown in FIGS. 4-6. Further, the control circuit80 controls the energizing of the solenoid 440 of the solenoid valve 44,thereby switching the position of the spool 443 to one of the positionsPa, Pr and Ph. Therefore, the flow of working oil is switched, based onthe position of the spool 443, relative to each first advance chamber 16a and each first retard chamber 16 r.

In the timing adjustment mode, when the negative torque Ta acts on thesecond vane rotor 30 in the advance direction from the camshaft 2,working oil of the second retard chamber 26 r is pressurized by thesecond vane 302 in the first vane 202. At this time, the working oil ofthe second retard chamber 26 r is restricted from flowing into thesecond advance chamber 26 a through the switch passage 72 but is allowedto flow into the second advance chamber 26 a through the check passage52.

On the other hand, when the positive torque Tr acts on the second vanerotor 30 in the retard direction from the camshaft 2, the working oil ofthe second advance chamber 26 a is pressurized by the second vane 302 inthe first vane 202. At this time, the working oil of the second advancechamber 26 a is restricted from flowing into the second retard chamber26 r through the switch passage 72 and is restricted from flowing intothe second retard chamber 26 r through the check passage 52.

As a result, working oil can be introduced into each second advancechamber 26 a, and can be discharged from each second retard chamber 26r, respectively. Thereby, the second vane 302 of the second vane rotor30 that has relative rotation in the advance direction relative to thefirst vane rotor 20 presses the internal surface 202 a of the first vane202 through the second retard chamber 26 r from which the working oil isdischarged, as shown in FIGS. 4-6.

Therefore, in the timing adjustment mode where the spool 443 is moved toone of the positions Pa, Pr, and Ph, the vane rotors 20 and 30 operatein the state where the second vane 302 is pressed to the first vane 202in the advance direction. That is, at the advance position Pa of FIG. 4,as shown in a blank arrow direction of FIG. 4, the second vane rotor 30and the first vane rotor 20 integrally have relative rotation in theadvance direction, relative to the housing 10. Further, at the retardposition Pr of FIG. 5, as shown in a blank arrow direction of FIG. 5,the second vane rotor 30 and the first vane rotor 20 integrally haverelative rotation in the retard direction, relative to the housing 10.Further, at the hold position Ph of FIG. 6, the second vane rotor 30 andthe first vane rotor 20 integrally rotate at the same speed as thehousing 10.

Thus, in the timing adjustment mode, in response to the switchovercontrol of working oil relative to each first advance chamber 16 a andeach first retard chamber 16 r, the housing 10 and the second vane rotor30 can be controlled to have a relative rotation phase, and a valvetiming corresponding to the relative rotation phase can be realized.Accordingly, the valve timing can be mechanically accurately adjusted inthe timing adjustment mode using the variation torque.

Furthermore in the timing adjustment mode, the check valve 64 restrictsthe working oil pressurized in the second advance chamber 26 a by thepositive torque Tr from flowing backward. That is, the working oil isrestricted from flowing from the supply point 720 to the pump 6 throughthe switch passage 72. In contrast, when the negative torque Ta isapplied, working oil can be supplied to the switch passage 72 throughthe supply point 720 from the pump 6 because the forward flow ispermitted by the check valve 64.

At this time, the solenoid valve 74 intercepts the communication in apart of the switch passage 72 between the supply point 720 and thesecond retard chamber 26 r. In contrast, working oil supplied to thesupply point 720 can flow to the second advance chamber 26 a in theother part of the switch passage 72 between the supply point 720 and thesecond advance chamber 26 a. Therefore, even if the working oilintroduced to the second advance chamber 26 a is leaked out from a slideclearance between the vane rotors 20 and 30, working oil supplied to thesupply point 720 can be supplied to the second advance chamber 26 a fromthe switch passage 72.

Thus, the state where the second vane 302 is pressed to the first vane202 can be maintained in the advance direction as a result of thebackflow regulation and the supply function, so that reliability can beraised for the accurate valve timing adjustment that is mechanicallyrealized in the state where the second vane 302 is pressed to the firstvane 202.

In addition, at the timing adjustment mode, because the second vane 302is disposed between the second advance chamber 26 a and the secondretard chamber 26 r, the length of the check passage 52 can be madeshort, so that the pressure loss can be decreased. Therefore, timeperiod necessary for pressing the second vane 302 to the first vane 202can be made short, so that the accurate valve timing adjustment can bequickly started in the timing adjustment mode.

(Working Angle Adjustment Mode)

When the apparatus 1 is set to have the working angle adjustment mode,the control circuit 80 controls the energizing of the solenoid 740 ofthe solenoid valve 74, thereby switching the switch passage 72 to allowthe communication between the second advance chamber 26 a and the secondretard chamber 26 r, as shown in FIGS. 7 and 8. Further, the controlcircuit 80 controls the energizing of the solenoid 440 of the solenoidvalve 44, thereby switching the position of the spool 443 to the holdposition Ph, as shown in FIGS. 7 and 8. Therefore, the flow of workingoil is regulated relative to the first advance chamber 16 a and thefirst retard chamber 16 r, and the regulation is continued from thestart to the end of the working angle adjustment mode.

The working angle adjustment mode is started from the state where thesecond vane 302 is pressed to the first vane 202 in the advancedirection in the previous timing adjustment mode. Specifically, when thepositive torque Tr acts on the second vane rotor 30 in the retarddirection from the camshaft 2, working oil of the second advance chamber26 a is pressurized by the second vane 302. At this time, the workingoil of the second advance chamber 26 a is restricted from flowing intothe second retard chamber 26 r through the check passage 52, but isallowed to flow into the second retard chamber 26 r through the switchpassage 72, as shown in FIG. 8.

Thus, the working oil is discharged from the second advance chamber 26a, and is introduced into the second retard chamber 26 r. Thereby, asshown in a blank arrow direction of FIG. 8, the second vane rotor 30that receives the positive torque Tr has relative rotation in the retarddirection relative to the first vane rotor 20, until the second vane 302is pressed to the internal surface 202 r of the first vane 202 throughthe second advance chamber 26 a from which the working oil isdischarged. At this time, the flow of working oil is regulated relativeto the first advance chamber 16 a and the first retard chamber 16 r, sothat the relative rotation of the first vane rotor 20 is regulatedrelative to the housing 10. Therefore, the second vane rotor 30 hasrelative rotation relative to the first vane rotor 20.

Thus, the positive torque Tr is consumed by the relative rotation of thesecond vane rotor 30 in a direction restricting the rotation of thecamshaft 2 until the second vane 302 is pressed to the first vane 202.In contrast, after the second vane 302 is pressed to the first vane 202,a force resisting to the positive torque Tr comes to act on the secondvane rotor 30 and the camshaft 2 from the first vane rotor 20.

Accordingly, as shown in FIG. 10, the valve-opening-operation thatgenerates the positive torque Tr is delayed in each exhaust valve thatis opened and closed by the camshaft 2 by a relative rotation angle“θer” until the second vane rotor 30 presses the second vane 302 to thefirst vane 202 in the retard direction. In an upper graph of FIG. 10, avalve lift amount represents a lift amount of the exhaust valve relativeto a crank angle that represents a rotation angle of the crankshaft. Inaddition, a solid line represents the valve lift amount according to thefirst embodiment, and a double-chain line represent a valve lift amountbefore having the valve characteristics control of the first embodiment,and the solid line and the double-chain line are shown in the overlapstate in a single graph of FIG. 10. In a lower graph of FIG. 10, therotation angle of the first vane rotor 20 and the rotation angle of thesecond vane rotor 30 according to the first embodiment are shownrelative to the crank angle.

Moreover, from the state of FIG. 8 in which the second vane 302 ispressed to the first vane 202 in the retard direction by the action ofthe positive torque Tr in the working angle adjustment mode, when thenegative torque Ta acts in the advance direction, working oil of thesecond retard chamber 26 r is pressurized by the second vane 302. Atthis time, the working oil of the second retard chamber 26 r ispermitted to flow into the second advance chamber 26 a through at leastone of the switch passage 72 and the check passage 52, as shown in FIG.7.

Thus, working oil can be introduced into the second advance chamber 26a, and can be discharged from the second retard chamber 26 r. Thereby,as shown in a blank arrow direction of FIG. 7, the second vane rotor 30that receives the negative torque Ta has relative rotation in theadvance direction relative to the first vane rotor 20, until the secondvane 302 is pressed to the internal surface 202 a of the first vane 202through the second retard chamber 26 r from which the working oil isdischarged. At this time, the flow of working oil is regulated relativeto the first advance chamber 16 a and the first retard chamber 16 r, sothat the relative rotation of the first vane rotor 20 is regulatedrelative to the housing 10. Therefore, the second vane rotor 30 hasrelative rotation relative to the first vane rotor 20.

Therefore, the negative torque Ta is consumed by the relative rotationof the second vane rotor 30 in a direction assisting the rotation of thecamshaft 2 until the second vane 302 is pressed to the first vane 202.In contrast, after the second vane 302 is pressed to the first vane 202,a force resisting to the negative torque Ta comes to act on the secondvane rotor 30 and the camshaft 2 from the first vane rotor 20.

Accordingly, as shown in FIG. 10, the valve-closing-operation thatgenerates the negative torque Ta is advanced in the exhaust valve thatis opened and closed by the camshaft 2 by a relative rotation angle“θea” until the second vane rotor 30 presses the second vane 302 to thefirst vane 202 in the advance direction.

Accordingly, from the start to the end of the working angle adjustmentmode, while the valve-closing-operation finishing timing “tec” ismaintained as shown in FIG. 10 by regulating the relative rotationbetween the housing 10 and rotor 20, a valve working angle “φe” can bereduced by the delay “θer” in the valve-opening-operation and theadvance “θea” in the valve-closing-operation. Thus, when thevalve-closing-operation finishing timing “tec” is maintained and whenthe valve working angle “φe” is reduced, as shown in FIG. 11, ablow-down pressure represented by a dashed line of FIG. 11 is restrictedfrom overlapping between the exhaust valve shown in the upper graph ofFIG. 11 and the exhaust valve shown in the lower graph of FIG. 11. InFIG. 11, the valve-opening-timing of the exhaust valve shown in theupper graph is earlier than that of the exhaust valve shown in the lowergraph.

If the blow-down pressure overlaps between the exhaust valve shown inthe upper graph of FIG. 11 and the exhaust valve shown in the lowergraph of FIG. 11, residual gas is increased. However, according to thefirst embodiment, the residual gas can be restricted from increasing byrestricting the overlapping in the flow-down pressure, so that thecombustion is restricted from getting worse. Moreover, according to theworking angle adjustment mode using the variation torque, the valveworking angle “φe” can be mechanically accurately adjusted. Furthermorein the working angle adjustment mode, the working oil pressurized by thepositive torque Tr or the negative torque Ta in the second advancechamber 26 a or the retard chamber 26 r can be restricted from flowingbackward. Specifically, the check valve 64 restricts the working oilfrom flowing from the supply point 720 to the pump 6 through the switchpassage 72. Even if the working oil introduced to the second retardchamber 26 r or the second advance chamber 26 a is leaked out from theslide clearance of the vane rotors 20 and 30, working oil can besupplied to the supply point 720 from the pump 6 through the switchpassage 72. Thus, the relative rotation of the second vane rotor 30 withrespect to the first vane rotor 20 can be realized alternately betweenthe retard direction and the advance direction until the second vane 302is pressed to the first vane 202, so that reliability can be raised inthe accurate control adjusting the valve working angle.

Second Embodiment

A valve characteristics control apparatus 2001 according to a secondembodiment is a modification example of the first embodiment, andcontrols valve timing and valve working angle for plural intake valveshaving different opening/closing timings, as valve characteristics of avalve. The second vane rotor 30 rotating with the camshaft 2 that opensand closes the intake valve receives variation torque that isalternately varied between the positive torque Tr and the negativetorque Ta, similarly to the first embodiment shown in FIG. 9.

(Working Angle Adjustment Mode)

When the apparatus 2001 is set to have the working angle adjustmentmode, the control circuit 2080 controls the energizing of the solenoid440 of the solenoid valve 44, thereby switching the position of thespool 443 to the advance position Pa, as shown in FIG. 12, and thenswitching the position of the spool 443 to the hold position Ph, asshown in FIGS. 13 and 14. Therefore, working oil is introduced into thefirst advance chamber 16 a and is discharged from the first retardchamber 16 r, in accordance with the start of the working angleadjustment mode, and the regulation of working oil relative to the firstadvance chamber 16 a and the first retard chamber 16 r is continued tothe end of the working angle adjustment mode. In addition, from thestart to the end of the working angle adjustment mode, the controlcircuit 2080 controls the energizing of the solenoid 740 of the solenoidvalve 74, thereby switching the switch passage 72 to allow thecommunication between the second advance chamber 26 a and the secondretard chamber 26 r, as shown in FIGS. 12-14, similarly to the firstembodiment.

The working angle adjustment mode is started from the state where thesecond vane 302 is pressed to the first vane 202 in the advancedirection in the previous timing adjustment mode. In accordance with thestart of the working angle adjustment mode, the spool 443 is moved tothe advance position Pa of FIG. 12, thereby, as shown in a blank arrowdirection of FIG. 12, the second vane rotor 30 and the first vane rotor20 integrally have rotation in the advance direction relative to thehousing 10. As a result, as shown in FIG. 15, thevalve-opening-operation starting timing “tic” and thevalve-closing-operation finishing timing “tic” are advanced by apredetermined advance amount “Δia” as a valve timing corresponding tothe relative rotation phase between the housing 10 and the second vanerotor 30.

In FIG. 15, a valve lift amount represents a lift amount of the intakevalve relative to a crank angle that represents a rotation angle of thecrankshaft. In addition, a solid line represents the valve lift amountof the intake valve having the advance in the valve-opening-operationstarting timing “tio” and the valve-closing-operation finishing timing“tic”, and a double-chain line represent a valve lift amount beforehaving the advance in the valve-opening-operation starting timing “tio”and the valve-closing-operation finishing timing “tic”. The solid lineand the double-chain line are shown in the overlap state in a singlegraph of FIG. 15.

After the advance operation of FIG. 15 is finished, when the spool 443is moved to the hold position Ph of FIGS. 13 and 14 in the state wherethe second vane 302 is pressed to the first vane 202 in the advancedirection, the valve-opening-operation is delayed and thevalve-closing-operation is advanced, similarly to the first embodiment.That is, as shown in FIG. 14, working oil is discharged from the secondadvance chamber 26 a and is introduced into the second retard chamber 26r, when the positive torque Tr is applied in the retard direction fromthe state shown in FIG. 13.

Accordingly, as shown in FIG. 16, the valve-opening-operation thatgenerates the positive torque Tr is delayed in the intake valve that isopened and closed by the camshaft 2 by a relative rotation angle “θir”until the second vane rotor 30 presses the second vane 302 to the firstvane 202 in the retard direction as shown in a blank arrow direction ofFIG. 14. According to the second embodiment, the apparatus 2001 isconstructed in a manner that the relative rotation angle “θir” becomesapproximately equal to the predetermined advance amount “Δia”.

In an upper graph of FIG. 16, a valve lift amount represents a liftamount of the intake valve relative to a crank angle that represents arotation angle of the crankshaft. In addition, a solid line representsthe valve lift amount according to the second embodiment, and adouble-chain line represent a valve lift amount before having the valvecharacteristics control of the second embodiment. The solid line and thedouble-chain line are shown in the overlap state in a single graph ofFIG. 16. In a lower graph of FIG. 16, the rotation angle of the firstvane rotor 20 and the rotation angle of the second vane rotor 30according to the second embodiment are shown relative to the crankangle.

In contrast, as shown in FIG. 13, working oil is introduced into thesecond advance chamber 26 a and is discharged from the second retardchamber 26 r when the negative torque Ta is applied in the advancedirection from the state of FIG. 14. Accordingly, as shown in FIG. 16,the valve-closing-operation that generates the negative torque Ta isadvanced in the intake valve that is opened and closed by the camshaft 2by a relative rotation angle “θia” until the second vane rotor 30presses the second vane 302 to the first vane 202 in the advancedirection as shown in a blank arrow direction of FIG. 13.

From the complete of the advance operation shown in FIG. 15 to the endof the working angle adjustment mode, the valve-closing-operationfinishing timing “tic” is maintained in the advance state by regulatingthe relative rotation between the housing 10 and rotor 20, as shown inFIG. 16. Further, a valve working angle “φi” can be reduced by the delay“θir” in the valve-opening-operation and the advance “θia” in thevalve-closing-operation.

Thus, as shown in FIG. 17, the valve working angle “φi” of the intakevalve is restricted from overlapping with the valve working angle “φe”of the exhaust valve when the valve-closing-operation finishing timing“tic” is maintained and when the valve working angle “φi” is reduced.Therefore, at a low-load time of the combustion engine, residual gas canbe restricted from increasing by restricting the overlapping in thevalve working angle, so that the combustion is restricted from gettingworse. Moreover, according to the working angle adjustment mode usingthe variation torque, the valve working angle “φi” can be mechanicallyaccurately adjusted, similarly to the first embodiment, due to thebackflow regulation and the supply function.

Third Embodiment

A valve characteristics control apparatus 3001 according to a thirdembodiment is a modification example of the first embodiment, andcontrols valve timing and valve working angle for plural intake valveshaving different opening/closing timings, as valve characteristics of avalve. The second vane rotor 30 rotating with the camshaft 2 that opensand closes the intake valve receives variation torque that isalternately varied between the positive torque Tr and the negativetorque Ta, similarly to the first embodiment shown in FIG. 9.

(Rotation Control System)

As shown in FIG. 18, the first check valve part 3050 has plural checkpassages 52 and plural check valves 3054. The check passage 52 isdefined to penetrate the corresponding second vane 302 so as to connectthe second advance chamber 26 a and the second retard chamber 26 r witheach other through the second vane 302. The check valve 3054 is arrangedin the middle of the check passage 52 in the corresponding second vane302. When the check valve 3054 is opened, working oil flows from thesecond advance chamber 26 a to the second retard chamber 26 r. Thereby,each check valve 3054 permits the forward feed of working oil which goesto the second retard chamber 26 r from the second advance chamber 26 a.On the other hand, the backward flow of working oil which goes to thesecond advance chamber 26 a from the second retard chamber 26 r isregulated by the check valve 3054. Thus, the check passage 52 and thecheck valve 3054 construct the first check valve part 3050, which isdisposed in each of the second vanes 302.

(Timing Adjustment Mode)

When the apparatus 3001 is set to have the timing adjustment mode,similarly to the first embodiment, the control circuit 80 controls theenergizing of the solenoid 740, 440, thereby switching the switchpassage 72 to prohibit the communication between the second advancechamber 26 a and the second retard chamber 26 r, as shown in FIGS.18-20. Further, the control circuit 80 switches the position of thespool 443 to one of the positions Pa, Pr and Ph. Therefore, the flow ofworking oil is switched, based on the position of the spool 443,relative to each first advance chamber 16 a and each first retardchamber 16 r.

In the timing adjustment mode, when the positive torque Tr acts on thesecond vane rotor 30 in the retard direction from the camshaft 2,working oil of the second advance chamber 26 a is pressurized by thesecond vane 302 in the first vane 202. At this time, the working oil ofthe second advance chamber 26 a is restricted from flowing into thesecond retard chamber 26 r through the switch passage 72 but is allowedto flow into the second retard chamber 26 r through the check passage52.

On the other hand, when the negative torque Ta acts on the second vanerotor 30 in the advanced direction from the camshaft 2, the working oilof the second retard chamber 26 r is pressurized by the second vane 302in the first vane 202. At this time, the working oil of the secondretard chamber 26 r is restricted from flowing into the second advancechamber 26 a through the switch passage 72 and is restricted fromflowing into the second advance chamber 26 a through the check passage52.

As a result, working oil can be discharged from each second advancechamber 26 a, and can be introduced into each second retard chamber 26r, respectively. Thereby, the second vane 302 of the second vane rotor30 that has relative rotation in the retard direction relative to thefirst vane rotor 20 presses the internal surface 202 r of the first vane202 through the second advance chamber 26 a from which the working oilis discharged, as shown in FIGS. 18-20.

Therefore, in the timing adjustment mode where the spool 443 is moved toone of the positions Pa, Pr, and Ph, the vane rotors 20 and 30 operatein the state where the second vane 302 is pressed to the first vane 202in the retard direction. That is, at the advance position Pa of FIG. 18,as shown in a blank arrow direction of FIG. 18, the second vane rotor 30and the first vane rotor 20 integrally have relative rotation in theadvance direction, relative to the housing 10. Further, at the retardposition Pr of FIG. 19, as shown in a blank arrow direction of FIG. 19,the second vane rotor 30 and the first vane rotor 20 integrally haverelative rotation in the retard direction, relative to the housing 10.Further, at the hold position Ph of FIG. 20, the second vane rotor 30and the first vane rotor 20 integrally rotate at the same speed as thehousing 10.

Thus, in the timing adjustment mode, in response to the switchovercontrol of working oil relative to each first advance chamber 16 a andeach first retard chamber 16 r, the housing 10 and the second vane rotor30 can be controlled to have a relative rotation phase, and a valvetiming corresponding to the relative rotation phase can be realized.Accordingly, the valve timing can be mechanically accurately adjusted inthe timing adjustment mode using the variation torque.

Furthermore in the timing adjustment mode, the check valve 64 restrictsthe working oil pressurized in the second retard chamber 26 r by thenegative torque Ta from flowing backward. That is, the working oil isrestricted from flowing from the supply point 720 to the pump 6 throughthe switch passage 72. In contrast, when the positive torque Tr isapplied, working oil can be supplied to the switch passage 72 throughthe supply point 720 from the pump 6 because the forward flow ispermitted by the check valve 64.

At this time, the solenoid valve 74 intercepts the communication in apart of the switch passage 72 between the supply point 720 and thesecond advance chamber 26 a. In contrast, working oil supplied to thesupply point 720 can flow to the second retard chamber 26 r in the otherpart of the switch passage 72 between the supply point 720 and thesecond retard chamber 26 r. Therefore, even if the working oilintroduced to the second retard chamber 26 r is leaked out from theslide clearance between the vane rotors 20 and 30, working oil suppliedto the supply point 720 can be supplied to the second retard chamber 26r from the switch passage 72.

Thus, the state where the second vane 302 is pressed to the first vane202 can be maintained in the retard direction as a result of thebackflow regulation and the supply function, so that reliability can beraised for the accurate valve timing adjustment that is mechanicallyrealized in the state where the second vane 302 is pressed to the firstvane 202.

In addition, at the timing adjustment mode, because the second vane 302is disposed between the second advance chamber 26 a and the secondretard chamber 26 r, the length of the check passage 52 can be madeshort, so that the pressure loss can be decreased. Therefore, theaccurate valve timing adjustment can be quickly started in the timingadjustment mode.

(Working Angle Adjustment Mode)

When the apparatus 3001 is set to have the working angle adjustmentmode, similarly to the first embodiment, the control circuit 80 controlsthe energizing of the solenoid 740, 440, thereby switching the switchpassage 72 to allow the communication between the second advance chamber26 a and the second retard chamber 26 r, as shown in FIGS. 21 and 22.Further, the control circuit 80 switches the position of the spool 443to the hold position Ph, as shown in FIGS. 21 and 22. Therefore, theflow of working oil is regulated relative to the first advance chamber16 a and the first retard chamber 16 r, and the regulation is continuedfrom the start to the end of the working angle adjustment mode.

The working angle adjustment mode is started from the state where thesecond vane 302 is pressed to the first vane 202 in the retard directionin the previous timing adjustment mode. Specifically, when the negativetorque Ta acts on the second vane rotor 30 in the advance direction fromthe camshaft 2, working oil of the second retard chamber 26 r ispressurized by the second vane 302. At this time, the working oil of thesecond retard chamber 26 r is restricted from flowing into the secondadvance chamber 26 a through the check passage 52, but is allowed toflow into the second advance chamber 26 a through the switch passage 72,as shown in FIG. 22.

Thus, the working oil is introduced into the second advance chamber 26a, and is discharged from the second retard chamber 26 r. Thereby, asshown in a blank arrow direction of FIG. 22, the second vane rotor 30that receives the negative torque Ta has relative rotation in theadvance direction relative to the first vane rotor 20, until the secondvane 302 is pressed to the internal surface 202 a of the first vane 202through the second retard chamber 26 r from which the working oil isdischarged. At this time, the flow of working oil is regulated relativeto the first advance chamber 16 a and the first retard chamber 16 r, sothat the relative rotation of the first vane rotor 20 is regulatedrelative to the housing 10. Therefore, the second vane rotor 30 hasrelative rotation relative to the first vane rotor 20.

Thus, the negative torque Ta is consumed by the relative rotation of thesecond vane rotor 30 in a direction assisting the rotation of thecamshaft 2 until the second vane 302 is pressed to the first vane 202.In contrast, after the second vane 302 is pressed to the first vane 202,a force resisting to the negative torque Ta comes to act on the secondvane rotor 30 and the camshaft 2 from the first vane rotor 20.

Accordingly, as shown in FIG. 23, the valve-closing-operation thatgenerates the negative torque Ta is advanced in each intake valve thatis opened and closed by the camshaft 2 by a relative rotation angle“θia” until the second vane rotor 30 presses the second vane 302 to thefirst vane 202 in the advance direction. In an upper graph of FIG. 23, avalve lift amount represents a lift amount of the intake valve relativeto a crank angle that represents a rotation angle of the crankshaft. Inaddition, a solid line represents the valve lift amount according to thethird embodiment, and a double-chain line represent a valve lift amountbefore having the valve characteristics control of the third embodiment,and the solid line and the double-chain line are shown in the overlapstate in a single graph of FIG. 23. In a lower graph of FIG. 23, therotation angle of the first vane rotor 20 and the rotation angle of thesecond vane rotor 30 according to the third embodiment are shownrelative to the crank angle.

Moreover, from the state of FIG. 22 in which the second vane 302 ispressed to the first vane 202 in the advance direction by the action ofthe negative torque Ta in the working angle adjustment mode, when thepositive torque Tr acts in the retard direction, working oil of thesecond advance chamber 26 a is pressurized by the second vane 302. Atthis time, the working oil of the second advance chamber 26 a ispermitted to flow into the second retard chamber 26 r through at leastone of the switch passage 72 and the check passage 52, as shown in FIG.21.

Thus, working oil can be discharged from the second advance chamber 26a, and can be introduced into the second retard chamber 26 r. Thereby,as shown in a blank arrow direction of FIG. 21, the second vane rotor 30that receives the positive torque Tr has relative rotation in the retarddirection relative to the first vane rotor 20, until the second vane 302is pressed to the internal surface 202 r of the first vane 202 throughthe second advance chamber 26 a from which the working oil isdischarged. At this time, the flow of working oil is regulated relativeto the first advance chamber 16 a and the first retard chamber 16 r, sothat the relative rotation of the first vane rotor 20 is regulatedrelative to the housing 10. Therefore, the second vane rotor 30 hasrelative rotation relative to the first vane rotor 20.

Therefore, the positive torque Tr is consumed by the relative rotationof the second vane rotor 30 in a direction restricting the rotation ofthe camshaft 2 until the second vane 302 is pressed to the first vane202. In contrast, after the second vane 302 is pressed to the first vane202, a force resisting to the positive torque Tr comes to act on thesecond vane rotor 30 and the camshaft 2 from the first vane rotor 20.

Accordingly, as shown in FIG. 23, the valve-opening-operation thatgenerates the positive torque Tr is delayed in the intake valve that isopened and closed by the camshaft 2 by a relative rotation angle “θir”until the second vane rotor 30 presses the second vane 302 to the firstvane 202 in the retard direction.

Accordingly, from the start to the end of the working angle adjustmentmode, while the valve-opening-operation starting timing “tio” ismaintained as shown in FIG. 23 by regulating the relative rotationbetween the housing 10 and rotor 20, a valve working angle “φi” can bereduced by the advance “θia” in the valve-closing-operation and thedelay “θir” in the valve-opening-operation.

Thus, similarly to the second embodiment shown in FIG. 17, the valveworking angle “φi” of the intake valve is restricted from overlappingwith the valve working angle “φe” of the exhaust valve when thevalve-opening-operation starting timing “tio” is maintained and when thevalve working angle “φi” is reduced. Therefore, at a low-load time ofthe combustion engine, residual gas can be restricted from increasing byrestricting the overlapping in the valve working angle, so that thecombustion is restricted from getting worse. Moreover, according to theworking angle adjustment mode using the variation torque, the valveworking angle “φi” can be mechanically accurately adjusted, similarly tothe first embodiment, due to the backflow regulation and the supplyfunction.

Fourth Embodiment

A valve characteristics control apparatus 4001 according to a fourthembodiment is a modification example of the third embodiment, andcontrols valve timing and valve working angle for plural exhaust valveshaving different opening/closing timings, as valve characteristics of avalve. The second vane rotor 30 rotating with the camshaft 2 that opensand closes the intake valve receives variation torque that isalternately varied between the positive torque Tr and the negativetorque Ta, similarly to the first embodiment shown in FIG. 9.

(Working Angle Adjustment Mode)

When the apparatus 4001 is set to have the working angle adjustmentmode, the control circuit 4080 controls the energizing of the solenoid440 of the solenoid valve 44, thereby switching the position of thespool 443 to the retard position Pr, as shown in FIG. 24, and thenswitching the position of the spool 443 to the hold position Ph, asshown in FIGS. 25 and 26. Therefore, working oil is discharged from thefirst advance chamber 16 a and is introduced into the first retardchamber 16 r, in accordance with the start of the working angleadjustment mode, and the regulation of working oil relative to the firstadvance chamber 16 a and the first retard chamber 16 r is continued tothe end of the working angle adjustment mode. In addition, from thestart to the end of the working angle adjustment mode, the controlcircuit 4080 controls the energizing of the solenoid 740 of the solenoidvalve 74, thereby switching the switch passage 72 to allow thecommunication between the second advance chamber 26 a and the secondretard chamber 26 r, as shown in FIGS. 24-26, similarly to the firstembodiment.

The working angle adjustment mode is started from the state where thesecond vane 302 is pressed to the first vane 202 in the retard directionin the previous timing adjustment mode that is realized similarly to thethird embodiment. In accordance with the start of the working angleadjustment mode, the spool 443 is moved to the retard position Pr ofFIG. 24, thereby, as shown in a blank arrow direction of FIG. 24, thesecond vane rotor 30 and the first vane rotor 20 integrally haverotation in the retard direction relative to the housing 10. As aresult, as shown in FIG. 27, the valve-opening-operation starting timing“teo” and the valve-closing-operation finishing timing “tec” areretarded by a predetermined retard amount “Δer” as a valve timingcorresponding to the relative rotation phase between the housing 10 andthe second vane rotor 30.

In FIG. 27, a valve lift amount represents a lift amount of the exhaustvalve relative to a crank angle that represents a rotation angle of thecrankshaft. In addition, a solid line represents the valve lift amountof the exhaust valve having the delay in the valve-opening-operationstarting timing “teo” and the valve-closing-operation finishing timing“tec”, and a double-chain line represent a valve lift amount beforehaving the delay in the valve-opening-operation starting timing “teo”and the valve-closing-operation finishing timing “tec”. The solid lineand the double-chain line are shown in the overlap state in a singlegraph of FIG. 27.

After the retard operation of FIG. 27 is finished, when the spool 443 ismoved to the hold position Ph of FIGS. 25 and 26 in the state where thesecond vane 302 is pressed to the first vane 202 in the retarddirection, the valve-closing-operation is advanced and thevalve-opening-operation is delayed, similarly to the third embodiment.That is, as shown in FIG. 26, working oil is introduced into the secondadvance chamber 26 a and is discharged from the second retard chamber 26r, when the negative torque Ta is applied in the advance direction fromthe state shown in FIG. 25.

Accordingly, as shown in FIG. 28, the valve-closing-operation thatgenerates the negative torque Ta is advanced in the exhaust valve thatis opened and closed by the camshaft 2 by a relative rotation angle“θea” until the second vane rotor 30 presses the second vane 302 to thefirst vane 202 in the advance direction as shown in a blank arrowdirection of FIG. 26. According to the fourth embodiment, the apparatus4001 is constructed in a manner that the relative rotation angle “θea”becomes approximately equal to the predetermined retard amount “Δer”.

In an upper graph of FIG. 28, a valve lift amount represents a liftamount of the exhaust valve relative to a crank angle that represents arotation angle of the crankshaft. In addition, a solid line representsthe valve lift amount according to the fourth embodiment, and adouble-chain line represent a valve lift amount before having the valvecharacteristics control of the fourth embodiment. The solid line and thedouble-chain line are shown in the overlap state in a single graph ofFIG. 28. In a lower graph of FIG. 28, the rotation angle of the firstvane rotor 20 and the rotation angle of the second vane rotor 30according to the fourth embodiment are shown relative to the crankangle.

In contrast, as shown in FIG. 25, working oil is discharged from thesecond advance chamber 26 a and is introduced into the second retardchamber 26 r when the positive torque Tr is applied in the retarddirection from the state of FIG. 26. Accordingly, as shown in FIG. 28,the valve-opening-operation that generates the positive torque Tr isretarded in the exhaust valve that is opened and closed by the camshaft2 by a relative rotation angle “θer” until the second vane rotor 30presses the second vane 302 to the first vane 202 in the retarddirection as shown in a blank arrow direction of FIG. 25.

From the complete of the retard operation of FIG. 27 to the end of theworking angle adjustment mode, while the valve-opening-operationstarting timing “teo” is maintained in the retard state by regulatingthe relative rotation between the housing 10 and rotor 20, as shown inFIG. 28. Further, a valve working angle “φe” can be reduced by the delay“θer” in the valve-opening-operation and the advance “θea” in thevalve-closing-operation.

Thus, when the valve-opening-operation starting timing “teo” ismaintained and when the valve working angle “φe” is reduced, similarlyto the first embodiment shown in FIG. 11, a blow-down pressurerepresented by a dashed line of FIG. 11 is restricted from overlappingbetween the exhaust valve shown in the upper graph of FIG. 11 and theexhaust valve shown in the lower graph of FIG. 11.

If the blow-down pressure overlaps between the exhaust valve shown inthe upper graph of FIG. 11 and the exhaust valve shown in the lowergraph of FIG. 11, residual gas is increased. However, according to thefourth embodiment, the residual gas can be restricted from increasing byrestricting the overlapping in the flow-down pressure, so that thecombustion is restricted from getting worse. Moreover, according to theworking angle adjustment mode using the variation torque, the valveworking angle “φe” can be mechanically accurately adjusted.

Other Embodiments

While the present disclosure has been described with reference topreferred embodiments thereof, it is to be understood that thedisclosure is not limited to the preferred embodiments andconstructions. The present disclosure is intended to cover variousmodification and equivalent arrangements. In addition, while the variouscombinations and configurations, which are preferred, other combinationsand configurations, including more, less or only a single element, arealso within the spirit and scope of the present disclosure.

Specifically, the valve characteristics control apparatus 1, 4001 of thefirst and fourth embodiment may be applied to only one exhaust valve orat least one intake valve. Further, the valve characteristics controlapparatus 2001, 3001 of the second and third embodiment may be appliedto only one intake valve or at least one exhaust valve.

Further, in the working angle adjustment mode of the apparatus 2001,4001 of the second and fourth embodiment, the communication between thesecond advance chamber 26 a and the second retard chamber 26 r throughthe switch passage 72 may be intercepted when the position of the spool443 is switched to the advance position Pa or the retard position Prbefore the position of the spool 443 is switched to the hold positionPh.

Furthermore, the above operation and advantage can be obtained if thefirst check valve part 50, 3050 is disposed in at least one second vane302 in the first to fourth embodiments. Otherwise, the first check valvepart 50, 3050 may be disposed in other part of the second vane rotor 30other than the second vane 302, or may be disposed outside of the secondvane rotor 30.

In addition, the main supply passage 42 ms and the sub supply passage 62ss may be made to communicate with each other not through the port 442ms, 442 ss in the first to fourth embodiments.

Such changes and modifications are to be understood as being within thescope of the present disclosure as defined by the appended claims.

1. A valve characteristics control apparatus that controls valvecharacteristics of a valve opened and closed by a rotation of a camshaftin accordance with a rotation of a crankshaft in an internal combustionengine, the apparatus comprising: a housing rotating with thecrankshaft; a first vane rotor having a first vane rotatably received inthe housing, a first advance chamber and a first retard chamber beingdefined by partitioning a space between the housing and the first vanein a rotation direction, the first vane rotor having a relative rotationwith respect to the housing in an advance direction when working fluidis introduced into the first advance chamber and when working fluid isdischarged from the first retard chamber, the first vane rotor having arelative rotation with respect to the housing in a retard direction whenworking fluid is discharged from the first advance chamber and whenworking fluid is introduced into the first retard chamber; a controlvalve part that switches a flowing direction of working fluid betweenthe first advance chamber and the first retard chamber in a timingadjustment mode adjusting valve timing as the valve characteristics, thecontrol valve part restricting working fluid from flowing between thefirst advance chamber and the first retard chamber in a working angleadjustment mode adjusting a valve working angle as the valvecharacteristics; a second vane rotor having a second vane rotating withthe camshaft in a state that the second vane is projected into the firstvane in the housing, a second advance chamber and a second retardchamber being defined by partitioning a space between the first vane andthe second vane in the rotation direction, the second vane rotor havinga relative rotation with respect to the first vane rotor in the advancedirection when working fluid is introduced into the second advancechamber and when working fluid is discharged from the second retardchamber, the second vane rotor having a relative rotation with respectto the first vane rotor in the retard direction when working fluid isdischarged from the second advance chamber and when working fluid isintroduced into the second retard chamber; a first check valve parthaving a check passage connecting the second advance chamber and thesecond retard chamber with each other, the check valve part allowingworking fluid to flow from the second retard chamber through the checkpassage to the second advance chamber, the check valve part restrictingworking fluid from flowing from the second advance chamber through thecheck passage to the second retard chamber; and a switch valve parthaving a switch passage connecting the second advance chamber and thesecond retard chamber with each other, the switch valve part allowing acommunication between the second advance chamber and the second retardchamber through the switch passage in the working angle adjustment mode,the switch valve part prohibiting the communication between the secondadvance chamber and the second retard chamber through the switch passagein the timing adjustment mode.
 2. The valve characteristics controlapparatus according to claim 1, wherein the control valve part restrictsworking fluid from flowing between the first advance chamber and thefirst retard chamber continuously from a start of the working angleadjustment mode to an end of the working angle adjustment mode.
 3. Thevalve characteristics control apparatus according to claim 2, whereinthe valve is a plurality of exhaust valves having different valveopening timings.
 4. The valve characteristics control apparatusaccording to claim 1, wherein the control valve part restricts workingfluid from flowing between the first advance chamber and the firstretard chamber continuously to an end of the working angle adjustmentmode, after working fluid is introduced into the first advance chamberand is discharged from the first retard chamber in response to a startof the working angle adjustment mode.
 5. The valve characteristicscontrol apparatus according to claim 4, wherein the valve is an intakevalve of the engine.
 6. The valve characteristics control apparatusaccording to claim 1, wherein the switch passage has a supply point towhich working fluid is supplied, and the switch valve part is located ata position adjacent to the second retard chamber rather than the supplypoint of the switch passage.
 7. The valve characteristics controlapparatus according to claim 6, further comprising: a second check valvepart having a supply passage that communicates with the supply point ofthe switch passage and a supply source of working fluid, wherein thesecond check valve part allows working fluid to flow from the supplysource to the supply point, and the second check valve part prohibitsworking fluid from flowing from the supply point to the supply source.8. A valve characteristics control apparatus that controls valvecharacteristics of a valve opened and closed by a rotation of a camshaftin accordance with a rotation of a crankshaft in an internal combustionengine, the apparatus comprising: a housing rotating with thecrankshaft; a first vane rotor having a first vane rotatably received inthe housing, a first advance chamber and a first retard chamber beingdefined by partitioning a space between the housing and the first vanein a rotation direction, the first vane rotor having a relative rotationwith respect to the housing in an advance direction when working fluidis introduced into the first advance chamber and when working fluid isdischarged from the first retard chamber, the first vane rotor having arelative rotation with respect to the housing in a retard direction whenworking fluid is discharged from the first advance chamber and whenworking fluid is introduced into the first retard chamber; a controlvalve part that switches a flowing direction of working fluid betweenthe first advance chamber and the first retard chamber in a timingadjustment mode adjusting valve timing as the valve characteristics, thecontrol valve part restricting working fluid from flowing between thefirst advance chamber and the first retard chamber in a working angleadjustment mode adjusting a valve working angle as the valvecharacteristics; a second vane rotor having a second vane rotating withthe camshaft in a state that the second vane is projected into the firstvane in the housing, a second advance chamber and a second retardchamber being defined by partitioning a space between the first vane andthe second vane in the rotation direction, the second vane rotor havinga relative rotation with respect to the first vane rotor in the advancedirection when working fluid is introduced into the second advancechamber and when working fluid is discharged from the second retardchamber, the second vane rotor having a relative rotation with respectto the first vane rotor in the retard direction when working fluid isdischarged from the second advance chamber and when working fluid isintroduced into the second retard chamber; a first check valve parthaving a check passage connecting the second advance chamber and thesecond retard chamber with each other, the check valve part allowingworking fluid to flow from the second advance chamber through the checkpassage to the second retard chamber, the check valve part restrictingworking fluid from flowing from the second retard chamber through thecheck passage to the second advance chamber; and a switch valve parthaving a switch passage connecting the second advance chamber and thesecond retard chamber with each other, the switch valve part allowing acommunication between the second advance chamber and the second retardchamber through the switch passage in the working angle adjustment mode,the switch valve part prohibiting the communication between the secondadvance chamber and the second retard chamber through the switch passagein the timing adjustment mode.
 9. The valve characteristics controlapparatus according to claim 8, wherein the control valve part restrictsworking fluid from flowing between the first advance chamber and thefirst retard chamber continuously from a start of the working angleadjustment mode to an end of the working angle adjustment mode.
 10. Thevalve characteristics control apparatus according to claim 9, whereinthe valve is an intake valve of the engine.
 11. The valvecharacteristics control apparatus according to claim 8, wherein thecontrol valve part restricts working fluid from flowing between thefirst advance chamber and the first retard chamber continuously to anend of the working angle adjustment mode, after working fluid isdischarged from the first advance chamber and is introduced into thefirst retard chamber in response to a start of the working angleadjustment mode.
 12. The valve characteristics control apparatusaccording to claim 11, wherein the valve is a plurality of exhaustvalves having different valve opening timings.
 13. The valvecharacteristics control apparatus according to claim 8, wherein theswitch passage has a supply point to which working fluid is supplied,and the switch valve part is located at a position adjacent to thesecond advance chamber rather than the supply point of the switchpassage.
 14. The valve characteristics control apparatus according toclaim 13, further comprising: a second check valve part having a supplypassage that communicates with the supply point of the switch passageand a supply source of working fluid, wherein the second check valvepart allows working fluid to flow from the supply source to the supplypoint, and the second check valve part prohibits working fluid fromflowing from the supply point to the supply source.
 15. The valvecharacteristics control apparatus according to claim 1, wherein thefirst check valve part is located inside the second vane.